1. Technical Field
The present invention generally relates to gas and/or liquid exchange. More particularly, the present invention relates to gas and/or liquid exchange between a first area within a bulk material pile and a second area outside the bulk material pile via a conduit connecting the first and second areas.
2. Background Information
When placed in a pile, bulk materials, such as organic solid waste, decompose or otherwise interact to create gases. For organic solid waste, the gases are principally methane and carbon dioxide, with small amounts of hydrogen sulfide, mercaptan and other trace gases. Landfills housing organic solid waste piles are a significant source of such gases, which are odorless, flammable, explosive, toxic and contribute to atmospheric deterioration. Combustion or other treatment of collected landfill gases is a common way to mitigate the negative effects of the raw gas emissions.
Existing commercially available gas extraction systems primarily include vertical drilled wells and associated piping and valves, which are installed only after a given section of the landfill is completely filled and capped. This may be many years after gas production is occurring at high rates in the waste mass, allowing a significant volume of solid waste gases to be emitted uncontrolled prior to installation of such systems. In addition, such vertical systems are prone to clogging.
More recently, trenches have been dug in existing solid waste piles, with piping (including perforated piping) and surrounding stone installed for gas removal. However, while this horizontal method is an improvement over vertical wells, this solution has its drawbacks. For example, the trenches are dug after a time when the solid waste pile has built up potentially dangerous gases and likely created an odor problem. Further, this after-the-fact solution requires additional effort (e.g., digging a trench) over a solution integrated into the formation of the solid waste pile.
Another problem is that low moisture content within a solid waste pile slows microbial activity, thus prolonging the time that the solid waste is in an unstable, dynamic biological state. This condition requires greater surveillance and maintenance efforts. Organic waste that is fully biostabilized, such as cured compost, is much more desirable, due to predictable settlement rates and reduced gas production.
Thus, a need exists for a way to provide gas and/or liquid exchange between an area within a bulk material pile and an area outside the bulk material pile.